Fecal Fat

Synonym/Acronym

stool fat, fecal fat stain.

Rationale

To assess for the presence of fat in the stool toward diagnosing malabsorption disorders such as Crohn disease and cystic fibrosis.

Patient Preparation

There are no fluid or activity restrictions unless by medical direction. Instruct the patient to ingest a diet containing 50 to 150 g of fat for at least 3 days before beginning specimen collection. This approach does not work well with children; instruct the caregiver to record the child’s dietary intake to provide a basis from which an estimate of fat intake can be made. Instruct the patient not to use laxatives, enemas, or suppositories for 3 days before the test. As appropriate, provide the required stool collection container, plastic bag to store container in refrigerator during the collection period, and specimen collection instructions; the test may require either a random specimen or a 72-hr collection. A large, clean, preweighed container should be used for the timed test. A smaller, clean container can be used for the collection of the random sample. Ensure specimen collection for this study is accomplished before any barium procedures are performed.

Normal Findings

Method: Stain with Sudan black or oil red O for qualitative evaluation; nuclear magnetic resonance spectroscopy for quantitative evaluation. Treatment with ethanol identifies neutral fats; treatment with acetic acid identifies fatty acids.

Age		Random, Qualitative
All ages		0%–19%
		24-hr, 48-hr, 72-hr, Quantitative
Age (normal diet)
Infant (breast milk)		Less than 1 g/24 hr
0–6 yr		Less than 2 g/24 hr
Adult		Less than 7 g/24 hr; less than 20% of total solids
Adult (fat-free diet)		Less than 4 g/24 hr

^* hpf = high-power field.

Critical Findings and Potential Interventions ⬆ ⬇

Overview ⬆ ⬇

(Study type: Fecal analysis, stool aliquot from an unpreserved and homogenized 24- to 72-hr timed collection; related body system: Digestive system. Random specimens may also be submitted.)

The semiquantitative test is used to screen for the presence of fecal fat. The quantitative method, which requires a 72-hr stool collection, measures the amount of fat present in grams.

Fecal fat consists primarily of triglycerides (neutral fats), fatty acids, and fatty acid salts. Through microscopic examination, the number and size of fat droplets as well as the type of fat present can be determined. Excretion of more than 7 g of fecal fat in a 24-hr period is abnormal but nonspecific for disease. Increases in excretion of neutral fats are associated with pancreatic exocrine insufficiency, whereas decreases are related to small bowel disease. An increase in triglycerides indicates that insufficient pancreatic enzymes are available to convert the triglycerides into fatty acids. Patients with malabsorption conditions have normal amounts of triglycerides but an increase in total fecal fat because the fats are not absorbed through the intestine. Malabsorption disorders (e.g., cystic fibrosis) cause blockage of the pancreatic ducts by mucus, which prevents the enzymes from reaching the duodenum and results in lack of fat digestion. Without digestion, the fats cannot be absorbed, and steatorrhea results. The appearance and odor of stool from patients with steatorrhea is typically foamy, greasy, soft, and foul smelling.

Indications ⬆ ⬇

Assist in the diagnosis of malabsorption or pancreatic insufficiency, as indicated by elevated fat levels.
Monitor the effectiveness of therapy.

Interfering Factors ⬆ ⬇

Cimetidine has been associated with decreased fecal fat in some patients with cystic fibrosis who are also receiving pancreatic enzyme therapy.
Some drugs cause steatorrhea as a result of mucosal damage. These include colchicine, kanamycin, lincomycin, methotrexate, and neomycin. Drugs and other substances that can cause an increase in fecal fat include aminosalicylic acid, bisacodyl and phenolphthalein (observed in individuals who misuse laxatives), and cholestyramine (in high doses).
Use of suppositories, oily lubricants, or mineral oil in the perianal area for 3 days before the test can falsely increase neutral fats.
Use of herbals with laxative effects, including cascara, psyllium, and senna, for 3 days before the test can falsely increase neutral fats.
Barium interferes with test results.
Failure to collect all stools may reflect falsely decreased results.
Ingestion of a diet too high or low in fats may alter the results.

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Increased In

Abetalipoprotein deficiency (related to lack of transport proteins for absorption)
Addison disease (related to impaired transport)
Amyloidosis (increased rate of excretion related to malabsorption)
Bile salt deficiency (related to lack of bile salts required for proper fat digestion)
Carcinoid syndrome (increased rate of excretion related to malabsorption)
Celiac disease (increased rate of excretion related to malabsorption)
Crohn disease (increased rate of excretion related to malabsorption)
Cystic fibrosis (related to insufficient digestive enzymes)
Diabetes (abnormal motility related to primary condition)
Enteritis (increased rate of excretion related to malabsorption)
Malnutrition (related to detrimental effects on organs and systems responsible for digestion, transport, and absorption)
Multiple sclerosis (abnormal motility related to primary condition)
Pancreatic insufficiency or obstruction (related to insufficient digestive enzymes)
Peptic ulcer disease (related to improper digestion due to low pH)
Pernicious anemia (related to bacterial overgrowth that decreases overall absorption and results in vitamin B₁₂ deficiency)
Progressive systemic sclerosis (abnormal motility related to primary condition)
Thyrotoxicosis (abnormal motility related to primary condition)
Tropical sprue (increased rate of excretion related to malabsorption)
Viral hepatitis (related to insufficient production of digestive enzymes and bile)
Whipple disease (increased rate of excretion related to malabsorption)
Zollinger-Ellison syndrome (related to improper digestion due to low pH)

Decreased In

N/A

Nursing Implications ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

Review the procedure with the patient.
Explain that a stool sample is needed for the test.
Discuss how this test can assist in the diagnosis of intestinal disorders.
Instruct the patient to collect each stool and place it in the 500-mL container during the quantitative timed collection period. Stress the importance of collecting all stools for the quantitative test, including diarrhea, over the timed specimen-collection period. Provide instruction not to urinate in the stool-collection container or to put toilet paper in the container.
Keep the container refrigerated in the plastic bag throughout the entire collection period.

Potential Nursing Actions

Investigate the patient’s health concerns that indicate a gastrointestinal (GI) disorder, diarrhea related to GI dysfunction, pain related to tissue inflammation or irritation, alteration in diet resulting from an inability to digest certain foods, or fluid volume deficit related to active loss.

After the Study: Implementation & Evaluation Potential Nursing Actions

Treatment Considerations

Instruct the patient with abnormal values on the importance of fluid intake and proper diet specific to the medical condition.
Help the patient and caregiver cope with long-term implications.

Clinical Judgement

Consider which cultural markers need to be addressed to emphasize the value of adapting diet to improve bowel health.

Follow-Up Evaluation and Desired Outcomes

Acknowledges contact information provided for the American Diabetes Association (www.diabetes.org), the Celiac Disease Foundation (https://celiac.org), the Crohn’s and Colitis Foundation of America (www.crohnscolitisfoundation .org), or the Cystic Fibrosis Foundation (www.cff.org).